This is a unique housing tandem roller assembly most often found on Andersen wood patio doors as well as a variety of other manufacturers of wood patio doors. It has tandem 1-1/4 inch concave or grooved steel ball bearing rollers set in line in a stamped steel housing with side adjustment . The housing has two top insert points and side locking tabs to hold it in place.
This is a roller assembly; 1 1/4" tandem steel ball bearing rollers in an adjustable steel housing assembly.